We went on our cruise with three children ages 5,9 and 13. All of us had been on the Disney cruise 2 years ago. All of the children rated the children's programs on the Splendour far above those on Disney. Our five year old asked every morning when he could go and I think he enjoyed his time there in the evenings almost as much as family time during the day.
We had a bit of a delay in boarding because the ship was late coming back to port from the previous cruise due to severe fog in the area the night before. The staff were very friendly and tried to make our wait as pleasant as possible. Fortunately, there is a lot to do in the area just around the pier, so we had fun while we waited.
I was worried about the vibration I had heard so much about. The only place you can feel it is in the dining room and it was very minor. The rooms were not lavish, but well-appointed,quiet and comfortable. We didn't have a balcony, but the window was big. Our cabin steward was excellent.